Plasmid mediated multidrug resistant salmonella enterica serovar typhi isolated from in and around Chennai, Tamilnadu - India

The purpose of this study is to evaluate the transfer of resistant markers through conjugation and transformation evaluation of transconjugate strains for stability of R – plasmid against different conditions like several passages and storage in different temperatures for different time period. Around 2423 clinical samples collected from hospitals and health centers in and around chennai, and 105 isolates confirmed for Salmonella enteric serovar typhi based on preliminary, biochemical and cultural characteristics. All isolates examined for susceptibility against 11 commonly used antibiotics using Kirby-Bauer method. The susceptibility of isolates is confirmed by giving the  various strength of antibiotics using tube agar dilution method and  calculated the Minimal Inhibitory Concentration (MIC) as per clinical laboratory standards institute (CLSI). In our study 5 different resistant markers used to evaluate transfer of resistant markers through conjugation and transformation using Escherichia coli ATCC 25922 as a standard strain. Among 5 resistant markers four found to be transferred through conjugation and transformation, Nalidixic acid resistance marker was not transferred by either of methods due to the chromosomal origin of Nalidixic acid resistance. The strains monitored for its stable nature of R - plasmid during several passage and storing strains at different temperatures. In conclusion, it’s observed that the stable nature of R-plasmid may increase chances of conjugational transfer of resistivity to next generation there by aiding the spread and maintains multi drug resistance of Salmonella enterica serovar typhi. So it is mandatory to modify treatment methodologies and also to maintain the valuable life of existing antibiotics available to treat typhoid fever.